Things I learned here Darren:
1) patch can be the hard way or eZ way... if you have to work to get it down the bbl, it is THOUGHT to improve accuracy, but if you screw up and forget powder, how do you get the ball back out? Working with looser patching can produce good accuracy as well, I've been taught...
Some like an ez seating ball, some like to work harder.
2) Charge depends. Does your gun have an ante chamber? The GPR does, and if that isn't full, you have dead air space between charge and ball...BAD news! Instructions on Gun say min of 50 of gradient of powder, but I never go that low, so I don't worry much...
3) a charge that gives accuracy and limits fouling is important for a 2nd follow up shot in hunting I'd think...
I personally have Never fired a cap lock so no clue on anything with them... I once or twice up 'home' had T/C Renegades and fired friends Hawkens (we had to use flint in PA) they had... We didn't know much, but I had 3f so that was what I used... I know they say 2f for 50 cal, but I had 3F and it worked fine... I don't know if the TC had an ante chamber or not but we stuffed at least 90 and I settled on 100 gr...I was impervious to recoil back then...490 ball and precut patches back then too... lubed with expensive "bore butter"... GAWD...

I fiddled to make sure the ball was centered on the precut patch but using strips now and cutting at the muzzle is a whole lot simpler...
I wish you well, of course...